Field of the Invention
The present invention relates to an imaging apparatus which detects an object in a field to be photographed with the use of an optical element and an image sensor; a method for controlling the same; and a program.
Description of the Related Art
In recent years, many imaging apparatuses are commercialized which detect an object such as a person existing in a field to be photographed, and can automatically adjust the focus of a photographing lens on the object.
The imaging apparatuses generally detect the object based on information on an image sensor which is formed of a CMOS, a CCD or the like. On the other hand, in recent years, a single-lens reflex camera is commercialized which adopts an image sensor that is formed of a CMOS, a CCD and the like for a photometric sensor for measuring a luminance of the field to be photographed, and not only measures the luminance but also detects a face of a person and the like. The single-lens reflex camera sends information on the detection result to a widely known phase difference detection type of focus detection unit, and thereby can automatically adjust the focus of the photographing lens on the object.
However, it is difficult to give an imaging performance which sufficiently reduces chromatic aberration and the like, to an optical element for photometry (photometric lens) that forms an image on a photometric sensor, by structuring the optical element from a plurality of lenses like the photographing lens, from the viewpoint of a camera size and a cost.
In addition, a material of the photometric lens is generally plastic, and the performance of forming an image on the surface of the photometric sensor occasionally results in being lowered due to a change of a temperature and the like.
Furthermore, it is difficult to provide a lens of which the aberration is sufficiently reduced, not only for the photometric lens but also for a photographing lens which is mounted on a mobile phone and a tablet, from the viewpoint of reduction in the size and the cost.
Because of this, when the object is detected with the use of a lens of which the imaging performance is not high, it becomes a problem for the lens how to enhance the performance for detecting the object. Incidentally, here, the case has been described as an example, where the object is detected, but also when a contrast for focusing is detected, a similar problem occurs.
In order to solve this problem, for instance, Japanese Patent Application Laid-Open No. 2012-34130 discloses a configuration which converts a change of an imaging state of an optical system due to a change of a temperature, into weights Wr, Wg and Wb that correspond to the respective primary color signals of R, G and previously stores the converted weights in an image processing unit, appropriately sets the weights Wr, Wg and Wb in response to the output of a temperature measuring element, and corrects the aberration, for the purpose of reducing the deterioration of an image quality due to the change of the temperature of the optical system.